Security telephone

ABSTRACT

A telephone security device is built into a telephone unit. The device includes a sensor to detect an intrusion into the area in which the telephone is located. Upon detection of an event, the device places the telephone off hook, and triggers the redial feature of the telephone. This causes the telephone to redial the last number that had been called. The telephone then remains in the off hook condition for a delay interval to allow the recipient of the call to listen, via the telephone, for any sounds indication that an actual intrusion has occurred. In order to arm the security deice, the user simply dials the number that is the intended recipient of the call, hang up, and switch on the sensor. Detection of a security event will then cause the last dialed number to be redialed

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority based upon ProvisionalApplication Filing No. 60/444,583, filed Feb. 3, 2003, titled ALARMTRANSMISSION APPARATUS, the entirety of which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to security systems, and morespecifically to a security device built into a telephone to protect anarea in which the telephone is located.

2. Description of the Prior Art

Numerous security devices have been built or proposed that incorporatetelephone devices. In particular, devices that allow a telephone set toprotect an area in which the telephone is located have been proposed inthe prior art.

Examples of such devices include the designs included in U.S. Pat. Nos.4,027,103 and 6,263,069. In accordance with typical prior art designs,these devices will dial out to a preprogrammed number when a securityevent of a pre-established type is detected.

As will be appreciated by those skilled in the art, many of the devicesheretofore proposed or made available add significant cost to the costof a normal telephone device. Also, security devices incorporated intotelephone devices are generally somewhat complicated to operate, leadingto frustration and mistakes on the part of the person using them.

Normal electronic telephones, which are not enhanced by any type ofsecurity device, are inexpensive and reliable. Further, operation of thesimple features of such phones is straightforward, and understood byalmost all of those who use them. It would be desirable to provide asecurity telephone that is simple for anyone to use.

Many security telephone devices provide various features regarding how asecurity event is handled. In many cases, the function to be performedin case of a security event is to call a specified number or numbers tonotify an appropriate person of the event. In the past, this call wasoften made to a police department or private security company.

However, the increase in the number of security systems being installedhas led to problems caused by calls to the police department. Anextremely large number of such automated calls turn out to be falsealarms, which taxes the ability of the police department to providenormal services, due to the time involved in checking out such falsealarms. As a result, many police departments no longer respond to callsplaced by automated security systems, or at least charge a hefty finefor a response that turns out to be a false alarm.

Many security systems therefore automatically place calls to a securitycompany, which will then take responsibility for checking out the causeof the call and contact the police department if an actual intrusion hasoccurred. However, these systems are also subject to a high percentageof false alarms, and can be relatively costly.

Telephone devices that incorporate the ability to place a call to apre-programmed number have been proposed. However, such devices arerelatively complex, and require that one or more numbers be programmedin advance. Programming and updating such numbers is a level ofcomplexity that many consumers resist, preventing such devices frombecoming widely accepted in the marketplace.

It would be desirable for a telephone security system to be incorporatedinto a standard telephone set, and add minimal overall cost to thedevice. It would further be desirable for such a system to provideflexibility for a user, and be extremely simple to use.

SUMMARY OF THE INVENTION

In accordance with the present invention, a telephone security device isbuilt into a telephone unit. The device includes a sensor to detect anintrusion into the area in which the telephone is located. Upondetection of an event, the device places the telephone off hook, andtriggers the redial feature of the telephone. This causes the telephoneto redial the last number that had been called. The telephone thenremains in the off hook condition for a delay interval to allow therecipient of the call to listen, via the telephone, for any soundsindication that an actual intrusion has occurred. In order to arm thesecurity deice, the user simply dials the number that is the intendedrecipient of the call, hang up, and switch on the sensor. Detection of asecurity event will then cause the last dialed number to be redialed.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself however, as well as apreferred mode of use, further objects and advantages thereof, will bestbe understood by reference to the following detailed description of anillustrative embodiment when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a block diagram illustrating operation of a preferredtelephone security device;

FIG. 2 is a block diagram of a preferred telephone security device;

FIGS. 3 and 4 are flow charts illustrating a preferred mode of operationof the telephone security system;

FIG. 5 is a block diagram of the preferred telephone security device;

FIGS. 6 and 7 are schematic diagrams of a preferred embodiment of thetelephone security device; and

FIG. 8 is a schematic diagram of a preferred telephone line interfaceand charging circuit for operating the device set forth in FIGS. 6 and7.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment set forth herein functions to efficientlyperform the desired functions of the telephone security device. Inparticular, the circuits described herein comprise a simple set ofadditional circuitry that is easily added to an existing telephonedevice. Alternatively, the functions set forth herein can beincorporated into a telephone control chip to minimize parts count andcost. Those skilled in the art will appreciate the variations that canbe made to the described device to perform its intended functions.

The device described below operates with a telephone that has anelectronic control circuit. The features provided by the existingtelephone include the ability to take the telephone set off hook byapplication of a voltage signal, and the ability to redial thepreviously dialed number by application of a second signal. Suchtelephone sets are widely available, and the redial function of the sethas become a common feature for standard telephones.

Referring to FIG. 1, a security telephone according to the presentinvention is connected to the telephone system in any known manner. Thesecurity telephone 10 includes a sensor (not shown) that sensesmovement, or some other security event, in the area near the telephone.Preferably, an IR or similar motion detector is used, so that movementnear the security phone 10 will trigger an event. Once an event istriggered, security phone 10 takes itself off hook, and triggers itsstandard redial feature. The last dialed number will then be dialed, andthe last called phone 14 will be called. Security phone leaves itselfoff hook for a predetermined period of time, for example one minute, sothat a person at the called phone can listen in and determine whethersomething needs to be done to respond to the alarm.

FIG. 2 shows a high level block diagram of a preferred security circuitbuilt into security phone 10. Sensor 16 is preferably in IR motionsensor, but can be any other sensor that is appropriate for performing adesired security function. Sensor 16 has an output connected todetection circuit 18, which determines the occurrence of a securityevent and operates selected functions of the telephone set. Inparticular, detection circuit 18 operates the off hook and redial inputsof telephone control circuit 20, which is generally a single integratedcircuit device used to control operation of the telephone. Telephonecontrol circuit 20 then connects to an outside line in a normal manner,and redials the last called number.

FIG. 3 illustrates operation of the preferred embodiment of the securitytelephone. The user of the device dials the number to be notified, waitsfor one or two rings, and then hangs up 32. Alternatively, aconversation can be held with a person at the called telephone beforehanging up. The called number would typically be a number of someonetasked with investigating security events, or an alternative number atwhich the user can be found. Examples of such numbers include a homenumber (for a security telephone at the office), a work number (for asecurity telephone at home), or a cell phone number.

After hanging up, the user arms the security device 34, preferably bysimply moving a security switch to the on position. The security devicethen generates a delay 36 to allow the user time to leave the area nearthe security telephone. After this delay, the security feature of thephone is armed and operational. The device waits for the sensor to betriggered 38, and initiates a security call out 40 when it does. At theconclusion of the security call out, the unit returns to its sensingstate to await future security events. The set will remain in this stateuntil it is disarmed by returning the security switch to the offposition.

FIG. 4 illustrates the operations involved in a security call out.First, the device takes the telephone off hook to enable an outgoingcall to be placed. This is preferably accomplished by applying anappropriate signal to an available input pin of the telephone controlcircuit. The unit waits for a dial tone 44, which is an optional step.If desired, the unit can move on to the next step, triggering the redialfunction of the telephone 46, without delay.

The redial function is triggered by applying a pulse signal to anappropriate pin of the telephone control circuit. This mimics theoperation of pressing the redial button on the telephone handset. Thetelephone control circuit will then redial the last called number. Adelay 48 is generated, so that the security telephone remains off hookfor a predetermined period of time, after which it is returned to its onhook state 50. The predetermined delay is selected to be long enough toallow the recipient of the security call out to listen to any soundsmade near the security telephone, and determine whether any additionalaction needs to be taken. Once the telephone is returned to the on hookstate, it is enabled to allow further security events to trigger anadditional call out.

FIG. 5 is a block diagram of a preferred circuit for implementing thesecurity features described above. Sensor 16 is connected to a signalconditioning circuit 60, the nature of which depends on the operatingspecifications of sensor 16. Signal conditioning circuit 60 provides anoutput to level detect circuit 62, which generates an output signal whenthe output from signal conditioning circuit 60 is high enough toindicate that a security event has occurred. For example, if sensor 16is an IR motion detector generating an amplitude modulated sinusoidaloutput, level detector 62 generates an output signal when the outputamplitude of signal conditioner 60 is high enough to indicate thatmotion within the area has been detected.

Trigger circuit 64 is connected to the output of level detector 62, andinitiates operation of off hook timer 66 and redial pulse generator 68.Off hook timer 66 is connected to an off hook input of the telephonecontroller, and generates a signal that takes the telephone off hook. Atimer within circuit 66 keeps the telephone set off hook for apredetermined period of time, at which point the set is placed back onhook.

Redial pulse circuit 68 generates a short redial pulse, and applies itto the redial input of the telephone control circuit. This pulse causesthe telephone control circuit to redial the last number dialed, aspreviously described.

FIGS. 6-8 provide a more detailed schematic diagram of the preferredcircuit. Referring to FIG. 6, sensor PIR1 is preferably an IR motiondetector, part number RE200B, available for order from glolab.com. PIR1generates a sinusoidal output that varies in amplitude responsive tomotion detected, with a higher amplitude output indicating motiondetection. U1A and U1B are OP-AMPS utilized as amplifiers to conditionthe signal generated by PIR1. The output from U1B is connected to thenegative and positive inputs, respectively, of U1C and U1D. Voltagedivider ladder 70 provides an input to U1B for voltage levelnormalization, and voltage reference levels to U1C and U1D.

U1C an U1D provide the level detect function described in connectionwith FIG. 5. When the peak to peak amplitude of the sinusoid output fromU1B is small, both U1C and U1D generate high outputs. When the peakamplitude output from U1B exceeds a preset limit, set by voltage divider70, the outputs of U1C and U1D both go low. Node 72 is normally high,but is drawn low when the outputs of U1C and U1D go low. This draws thevoltage at node 74 low for a short time defined by the time constant ofR16 and C11.

Pulling the voltage at node 74 low triggers U2, preferably a 555 timer,to generate a pulse output on output pin 3. U2 preferably generates apulse of approximately 200 ms, which is set by R15 and C10, connected topins 6 and 7 as known in the art. This pulse is the signal OFF_HOOK,which indicates that a security event has been sensed. U2 and theassociated circuitry correspond to trigger 64 in FIG. 5.

The signal DISABLE, generated as described below by the circuitry ofFIG. 7, is used to disable U2 by forcing the voltage at node 74 toremain high. This prevents the 555 from triggering and generatinganother OFF_HOOK output pulse. When DISABLE is brought low, a voltage isgenerated across the base-emitter junction of Q3, turning Q3 on andconnecting node 74 to VCC (high).

Referring to FIG. 7, the circuits for off hook timer 66 and redial pulsetimer 68 are depicted. The OFF_HOOK pulse output from U2 charges upcapacitors C13 and C14, connected to the inputs of n-channel transistorsQ1 and Q2, respectively. C13 and C14, with associated resistors R17 andR19, respectively, determine time constants for how long Q1 and Q2 willbe turned on by the voltages at their respective gates.

When OFF_HOOK goes high, C13 and C14 charge up to VCC, turning on bothQ1 and Q2 and pulling the voltage at their respective drains to ground.This activates relay switches CR_HOOK_1 and CR_HOOK_2, driven by Q1, andCR_REDIAL, driven by Q2. LED1 and LED2 are optional, and are used toindicate that the security feature has been triggered. When OFF_HOOKgoes low after 200 ms, C13 and C14 discharge through R17 and R19,respectively. In the example embodiment shown, R17 is ten times as largeas R19, so capacitor C14 discharges in approximately one-tenth the timeas C13.

When C14 goes low, Q2 turns off and the voltage at its drain goes high.This turns off relay CR_REDIAL, completing a pulse started when Q2turned on. CR_REDIAL is connected to the redial input on the telephonecontroller chip, and upon completion of the pulse triggers the redialfeature of the telephone. The delay caused by the discharge of Q2ensures that a dial tone has been acquired before the redial isinitiated.

When Q1 turns on, DISABLE is pulled low as previously described. Thisprohibits U2 from being triggered again while the phone is in the offhook condition. (If such were to happen, additional redials could beinitiated during a single off hook period.) Q1 turning on also switchesrelays CR_HOOK_1 and CR_HOOK_2 on, placing the set into an off hookcondition. The phone remains in the off hook state until C13 dischargesand Q1 turns off.

FIG. 8 illustrates preferred circuitry for interfacing with thetelephone line, and charging a battery used to provide power to thecircuitry. As shown, CR_HOOK_1 and CR_HOOK_2 are switched by Q1, andconnect to the hook input of the telephone control chip to take thephone off hook when activated. Trickle charge circuitry 76 provides alow current trickle to charge BAT1 and BAT2, which provide VCC duringoperation of the security circuitry. Q5 and Q6 provide a current of lessthan approximately 3 mA until BAT1 and BAT2 are charged, allowing thecircuit to be charged through the telephone lines. If desired, as analternative a power supply can be provided that operates off of wallvoltages, but the design shown in FIG. 8 allows the unit to be extremelycompact and included in a standard telephone handset.

A portion of trickle charge circuitry 76 acts as a high voltagerejection circuit 78. Transistors Q5 and Q6 operate to allow the tricklecharging current through under normal operating conditions, but to blockcurrent during high voltage situations, such as occur when a ringvoltage is present on the line. When the incoming voltage is high enoughto overcome zener diode ZD1 and turn Q6 fully on, the base of Q5 ispulled to ground and Q5 turns off. This protect the batteries from highcurrent draw, and prevents the device from drawing more current than isallowed by telephone company specifications.

Switch T_ON/OFF is the arming switch set by the user, and connects thebatteries to VCC only when the switch is set. The remainder of the time,the security circuitry is disabled by removing its power supply.

It will be appreciated by those skilled in the art that the controlcircuitry described herein is an illustrative preferred embodiment, andthat other circuitry performing the same functions may be devised. Forexample, the circuitry described herein is intended to retrofit anexisting telephone set, and is therefore provided as circuitry externalto the existing telephone control chip. However, it is also useful toincorporate the functions described herein into the design of thetelephone control chip itself, which would necessitate various changesto operate with the internal circuitry of the controller.

Although the preferred embodiment has described the use of a motionsensor, other sensors can be used if desired. For example, sound orsmoke detectors could be used, as well as any sensor that responds tochanges in air pressure. A sensor could be wired to a door or window, orto trigger the device when an electric eye beam or other indicator istripped. Also, although the preferred sensor is an IR motion sensor,other types of motion sensors that respond to other modes of sensing,such as ultrasound, can be used if desired. When any different type ofsensor is used, the signal conditioning 60 and level detect circuitry 62will need to be modified to properly interface with the sensor actuallyused.

The preferred embodiment is designed to be added to a simple electronictelephone set such as is widely available. However, it can be adapted tobe included in a cordless telephone, either in the base unit or theportable unit as desired, as will be appreciated by those skilled in theart. If added to the base unit of a cordless telephone, many designswill require that the base unit be able to send an appropriate signal tothe portable unit to trigger the redial feature as described herein.

The described security device is very simple and inexpensive to produce,and can be retrofit to an existing telephone, or incorporated into a newdevice. In operation, the user need merely dial the number to which anotification call is desired, and arm the device by setting a singleswitch. The security device takes advantage of the pre-existing redialfeature of the phone, and does not require the usual relatively complexinterfacing and operation heretofore known in the prior art. Thisresults in a flexible and marketable product that answers a securityneed that has heretofore not been addressed.

Additional features can be incorporated into the device if desired.Using the described circuitry, each telephone set is independent, and itis possible that two separate extensions on a single line could betriggered independently by a single intruder. This would cause thesecond phone to redial while the first phone was already off hook, andpossibly being monitored by the recipient of the call. This might bedesirable in some circumstances, as the total time that the area wasmonitored would increase (the second phone would remain on line when thefirst hung up), but not in others. A circuit for sensing that the linewas already active could be used to suppress triggering the redial, ifdesired, to address this issue.

While the invention has been particularly shown and described withreference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.

1. A telephone security device, comprising: a telephone having ahousing, and capable of being used by a user to place telephone calls toany desired number over a telephone line; an electronic controllerwithin the telephone housing, such controller having an off-hook inputthat, when activated, places the telephone handset in an off-hookcondition, and further having a redial input that, when activated,causes the telephone to dial out, over an external telephone line, alast number previously dialed from the telephone; a sensor within thetelephone housing for detecting an event in an area near the telephonehandset; a switch on the telephone housing, having a first position anda second position, wherein the switch places the device into a securityactive state when in the first position, and in a security disabledstate when in the second position; a control circuit, within the housingand connected to the switch, and connected to the sensor and to theelectronic controller for, when the sensor detects an event while thedevice is in the security active state, activating the off-hook input,and activating the redial input while the telephone handset is in anoff-hook condition; wherein the off-hook input and redial input are notactivated when the device is in the security disabled state. 2.(canceled)
 3. The telephone security device of claim 1, wherein thesensor comprises an infrared motion sensor.
 4. The telephone securitydevice of claim 1, wherein the sensor comprises a sound detector.
 5. Thetelephone security device of claim 1, wherein the sensor comprises asmoke detector. 6-9. (canceled)
 10. (canceled) 11-18. (canceled)
 19. Thetelephone security device of claim 1, wherein the electronic controllercomprises an integrated circuit chip, and wherein the control circuit isincorporated into the integrated circuit chip.
 20. The telephonesecurity device of claim 1, wherein the electronic controller comprisesan integrated circuit chip, and wherein the control circuit is aseparate circuit external to the integrated circuit chip.
 21. Thetelephone security device of claim 1, wherein the off-hook input isactivated for a selected time period.
 22. The telephone security deviceof claim 1, wherein moving the switch from the second position to thefirst position places the device into the security active state onlyafter a delay period.